1. Field of the Invention
The invention relates to a solar photovoltaic junction box for collecting and outputting power generated by each of solar cell strings of a solar cell array, and in particular, to a solar photovoltaic junction box with a function of determining malfunction such as failure, etc., in a solar cell array.
2. Description of the Related Art
The Patent Literature 1 is a conventional method of determining malfunction such as failure, etc., in a solar cell array. Note that, the solar cell array is provided with plural solar cell strings each of which is formed by connecting plural solar cell panels in series.
The Patent Literature 1 discloses a method in which a defect location in a solar cell string is detected by measuring capacitance of the solar cell string. However, the Patent Literature 1 has a problem that it is not possible to determine malfunction in the solar cell string while the solar cell string is generating power since the capacitance of the solar cell string needs to be measured in a state of being separated from a system
On the hand, in a solar photovoltaic system having a solar cell array provided with plural solar strings, a solar photovoltaic junction box (also called combiner box) which collects power generated by each solar cell string and outputs the power to a power conditioner, etc., is generally used.
An example of a conventionally used solar photovoltaic junction box is shown in FIG. 6.
A solar photovoltaic junction box 61 shown in FIG. 6 is provided with plural input branch lines H electrically connected to respective solar cell strings 102 and an output aggregate line 12 which converges the plural branch lines 11 to collect power input from each of the solar cell strings 102 via the plural branch lines 11 and to output the power to a power conditioner 13, etc. FIG. 6 shows an example in which a solar cell array 101 is composed of four solar cell strings 102 and each solar cell string 102 is composed of four solar cell panels 103.
A back-flow preventing diode 14 for blocking a current flowing from the aggregate line 12 toward the solar cell string 102 is provided on each of the branch lines The back-flow preventing diode 14 is to prevent back-flow of the current caused by a difference in voltage level between the individual solar cell strings 102.
In addition, a branch line-side breaker 15 is each provided on the branch lines 11 to individually shut off the solar cell strings 102. An aggregate line-side breaker 16 is provided on the aggregate line 12 to shut off the entire solar cell array 101
The related art to the invention may include Patent Literature 1 (JP-A-2008-91828), Patent Literature 2 (JP-A-2011-66320), Patent Literature 3 (JP-A-2001-68706), and Patent Literature 4 (Japanese patent No. 3754898),